Coupling for rock drill



Sept. 15 1959 SCHNEIDER 2,904,312

' COUPLING FOR ROCK DRILL Filed March 5,. 1957 Fig.2

Jacob Schneider l Patent Patented Sept. 15, 1959 2,904,312 COUPLING FOR ROCK DRILL Jacob Schneider, Philipshurg, Mont. Application March 5, 1957, Serial No. 644,054 2 Claims. or. 255- 64) "This invention relates in general to new and useful improvements in drilling equipment for rock and other hard formations, and more specifically to an improved coupling to be disposed between the drill rod and the drill bit.

During the drilling of a hole in rock and other hard formations, after the passage of the drill bit down into the hole, and particularly during the withdrawal operation, portions of the formation oftentimes fall into the hole and become wedged between the upper portion of the drill bit and the wall of the hole therefore greatly in creasing the pulling power which must be exerted to extract the drill rod and the drill bit. Also, when cutting in sticky materials, the materials have a tendency to build up around the drill rodand form a collar within the hole. Inasmuch as the hole is normally cleared by utilizing either air or water under pressure, this is insufiicient to remove large particles of the formation from the hole and to properly clear the collar which may be formed in the hole. Further, when the hole becomes crooked, it is extremely diflicult to withdraw the drill rod and drill bit.

It is therefore the primary object of this invention to provide an improved coupling which will be disposed between the drill rod and the drill bit, the coupling being similar in configuration to the drill bit, but being inverted and having cutting edges at the upper end thereof whereby particles which may fall into the hole may be prevented from engaging and jamming between the drill bit and the wall of the hole and may be drilled out by a coupling during the withdrawal operation.

Another object of this invention is to provide an improved coupling for use between the lowermost section of 'drill rod and a drill bit, the coupling having the same general configuration as the drill bit, but being inverted, the coupling including wings which generally correspond in number to the wings of the drill bit with chipways between the wings being smaller than the chip ways of the drill bit whereby any particles in the formation passing through the chipways of the coupling are small enough to fall between the chipways of the drill bit and thus avoid jamming of the drill bit during the withdrawal operation.

A further object of this invention is to provide a coupling to be disposed between a drill bit and the drill rod therefor, the coupling having the same general configuration as the drill bit, but being inverted, the coupling forming an extension of the drill bit and thus effectively providing a relatively long drill bit body to assure the proper alignment of the drill bit at all times and thus avoid the drilling of crooked holes.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawing forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

Figure 1 is a perspective view of the coupling and shows the general configuration thereof;

2 Figure 2 is a fragmentary vertical sectional view taken through a hole which has been drilled and shows the relative position of the coupling with respect to the drill rod and the drill bit; and

Figure 3 is a schematic view showing the relation between the coupling andthe drill bit which permits a proper clearing of the hole and the withdrawal of the drill bit under all conditions of drilling operations.

Referring now to the drawing in detail, it will be seenthat there is illustrated in Figure 1 the coupling which is the subject of this invention, the coupling "being referred to in general by the reference numeral 10. The coupling 10 includes an elongated body 12 which terminates at its lower end in a reduced, externally threaded shank 14. The upper end of the body 12 is provided with an internally threaded socket 16.

It is to be noted that the coupling 10 has the general appearance of a drill bit which has been inverted. The body 12 of the coupling 10 is provided at the upper end thereofwith a plurality of radiating wings 18. The Wings 18 .taper downwardly and terminate into the body 12 at the lower end thereof. The wings 18 are provided at the upper ends thereof with cutting edges 20. If desired, the wings 18 may be provided with suitable inserts such as carbide inserts to facilitate a drilling operation. As in the case of a drill bit, the body 12 is cut away "between the wings 18 to form chipways 22.

Referring now to Figure 2, it will be seen that there is illustrated a drill string 24. The drill string 24 includes a drill rod 26 having a central bore 23 with a downward passage of water or air for purposes of clearing the hole being drilled. The lower end or" the drill rod '26 terminates in .an externally threaded portion 30. The externally threaded portion 30 is received within the socket L6 of the coupling 10. It is also to be noted that the coupling 10 is provided with a central bore 32 which is aligned with the bore 28 for receiving air or water under pressure from the drill rod 26.

Coupled to the lower end of the coupling 10 is a conventional rock drill bit 34. The rock drill bit 34 includes a body 36 having an internally threaded socket 38 formed in the upper end thereof. Threadedly engaged in the socket 38 is the shank 14 of the coupling 10. The body 36 of the drill bit 34 is provided with a bore 40 therethrough which is aligned with the bore 32 of the coupling 10.

As is best shown in Figures 2 and 3, the drill bit 34 is provided at the lower end thereof with radiating wings 42 which are separated by chipways 44. The wings 42 terminate at their lower ends in carbide inserts 46 presenting cutting edges 48 for the drilling operation. Inasmuch as the drill bit 34 is conventional, a further description thereof is believed to be unnecessary for the purposes of this invention.

During a normal drilling operation with the drill bit 34, the drill bit 34 is rotated by means of the drill rod 26. As cuttings from the formation being drilled are deposited in the lower end of the hole 50, these deposits are flowed upwardly through the chipways 44 and out through the hole 50 by means of compressed air or water under pressure being forced downwardly through the bores 28, 32 and 40. When drilling in the rock formation, oftentimes small particles of the formation drop into the hole 50 which are of a size to prevent their passage through the chipways 44. This results in many instances in the jamming of the rock particles between the upper portion of the body 36 and the wall of the hole 50 and thus requires a great increase in the pulling power to withdraw the drill string 24. By providing the coupling 10 and making the wings 18 of the coupling 10 of a greater width than the wings 42 and the chipways 22 of the coupling 10 smaller than the chip- 3 ways 44 of the drill bit 34, this condition is eliminated. The chipways 22 being smaller than the chipways 44, any particles passing through the chipways 22 will automatically pass through the chipways 44 and clear the drill bit 34. On the other hand, particles which are larger than the chipways 22 will be contacted by the cutting edges 20 and will be drilled out if they have a tendency to jam between the coupling wall of the hole 50.

During the drilling operation, in many instances the formation, when combining with water, forms a sticky mixture which results in a collar being formed above the drill bit. When the drill bit is to be withdrawn, it is necessary to break through that collar. By pro viding the cutting edges 20 on the upper end of the coupling 10, during the withdrawal operation, the coupling may be used to drill through these collars and thus reduce the pulling power required to withdraw the drill spring 24.

It is to be noted that the coupling 10 has been illustrated in Figures 2 and 3 as being of a smaller gauge than the drill bit 34. While this is not necessary, this does permit freedom of rotation of the coupling 10 without binding in the hole 50. It is not necessary that the difference in gauge between the coupling 10 and the drill bit 34 be as marked as that illustrated, and in certain instances the gauge of the coupling 10 may be the same as that of the drill bit 34. The provision of the coupling 10 also serves to increase the effective guiding length of the drill bit 34 and thus permits the drill bit 34 to follow the original line of the 'hole 50. This greatly facilitates the drilling of straight holes particularly in soft rock which overlies hard rock at an angle.

As will be readily apparent from the drawing, the coupling 10 may be readily inserted in a drill string between the lowermost drill section and the drill bit. Thus no adaptation of the existing drill strings must be made except for the placement of the coupling. Further, when it is not desired to utilize the coupling 10, it is merely necessary to eliminate it from the drill string prior to the drilling operation.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications may be resorted to, falling Within the scope of the invention as claimed.

What is claimed as new is as follows:

1. In combination with a drill bit for rock and hard formations, a coupling, said drill bit having an internally threaded socket in its upper end, said coupling comprising an elongated body, a central bore through said 10 and the body, said body being provided at its lower end with a reduced externally threaded shank received in said drill bit socket, an internally threaded socket in the upper end of said body for receiving a threaded lower end of a drill rod, said body including radiating wings along the upper portion thereof, chipways between adjacent wings for the passage of small material, said wings terminating at upper ends in cutting edges whereby said coupling may be used in a reverse drilling operation during the withdrawal of said drill bit, said drill bit having wings corresponding in number to the number of said coupling wings, chipways between said drill bit wings, said coupling wings being wider in directions normal to the radial centers thereof than said drill bit wings and said coupling chipways being of a smaller cross section than said drill bit chipways whereby material falling into the hole being drilled which will pass said coupling will also pass said drill bit and not jam between said drill bit and the wall of the hole.

2. In combination with a drill bit for rock and hard formations, a coupling, said drill bit having an internally threaded socket in its upper end, said coupling comprising an elongated body, a central bore through said body, said body being provided at its lower end with a reduced externally threaded shank received in said drill bit socket, an internally threaded socket in the upper end of said body for receiving a threaded lower end of a drill rod, said body including radiating wings along the upper portion thereof, chipways between adjacent wings for the passage of small material, said wings terminating at upper ends in cutting edges whereby said coupling may be used in a reverse drilling operation during the withdrawal of said drill bit, said drill bit having wings corresponding in number to the number of said coupling wings, chipways between the drill bit wings, said cou pling wings being wider in directions normal to the radial centers thereof than said drill bit wings and said coupling chipways being of a smaller cross section than said drill bit chipways whereby material falling into the hole being drilled which will pass said coupling will also pass said drill bit and not jam between said drill bit and the wall of the hole, the gauge of said coupling being slightly less than the gauge of said drill bit. 

